On Thu, Jul 23, 2015 at 8:58 PM, Christopher Havel laserhawk64@gmail.com wrote:
Ah. In that case...
Small rectangular notch in one side of each hinge barrel (I think barrel's the term... the part that goes around the pin). Little teeny ball bearing (like 2-3mm dia, you know, the sort of stuff you find in a BB gun) with a stiff spring behind it (either a coil spring, or a leaf spring with a long lip and a dimple to hold the BB). One on each side ought to do it. You can even have the notch on the same side for both hinges, if there's room... if not, I say notch both sides of the hinge so it'll work in either direction.
yeahhh you remember i said there's an 8mm barrel to work with? that's the outer dimensions. printing a part to fit in there needs to be a maximum of a 37mm radius, and there's a 20mm diameter bolt down the middle as well.
but the accuracy of the printer is, when creating parts, esp. complex ones, limited to about 1.5mm *if that*.
so there's no way i would be able to fit even a 1.5mm diameter ball bearing inside... and still have it be strong enough. the only way i'm confident about what i've created with the friction hinge that i've designed is that it's reasonably chunky. when i made things too thin (1.5mm or below) they just... broke off.
no, what i considered reasonable would be to have a D-shaped ring which you push-fit onto one end of the friction hinge, then house a simple flat spring that bends against the D.
when the spring hits the flat of the D, that's when it helps keep the lid closed.
when it's bent, it helps act as a friction hinge.
.... but even just sourcing steel flat springs and D-shaped rings i just... i can't be having with it. i've had enough. really. i want this done, and i want it out the door, no delays dealing with suppliers or with creating experimental prototype mechanical custom-made custom-machined parts.
i have a 3d printer, i have some 2mm threaded bar, i have some M2 8mm screws, and i have a spring from a biro. once product is sold, *then* we can get fancy.
l.